The adult colon is approximately 6 feet long and extends from the cecum to the rectum via the ascending, transverse, descending and sigmoid colons. Lesions resulting from a number of different disease conditions, such as colon cancer, ulcerative colitis and other inflammatory bowel diseases, can arise at any position along the length of the colon. Diagnosis of these different conditions typically involves visual examination of the colon using, for example, a colonoscope. A typical colonoscope comprises, at its proximal end, a light source, a video chip, and a suction channel. These elements are all in communication with the distal end of the colonoscope via wires and channels housed within a flexible tube. The proximal end of a typical colonoscope is shown in FIG. 1. The proximal end is inserted into a patient's rectum and can be maneuvered along the length of the colon. A colonoscope can be inserted far enough into a patients colon for the proximal end of the colonoscope to enter the patient's cecum. The tip of the colonoscope can also be maneuvered through the ileo-cecal valve into the terminal ileum. Colonoscopes provide a visual image only of the region of the colon that is immediately proximal to the light source and video chip. Lesions in a patient's colon typically are identified by progressive and painstaking visual examination of the entire colon. Various attachments to a colonoscope allow small surgical procedures, such as tissue biopsies, to be carried out during a colonoscopic examination. For example, U.S. Pat. No. 5,423,830 reports a polyp retrieval instrument assembly attached to a colonoscope.
Colonoscopes have also been used for therapeutic purposes, for example to relieve the cecal pressure buildup associated with colonic pseudo-obstruction or Ogilvie's syndrome. Martin, et al., The American Surgeon, 54: 519-521 (1988). Patients suffering from Ogilvie's syndrome typically present an acutely distended colon, and a distended cecum in particular. These symptoms result from an accumulation of gas in the lumen of the colon. Insertion of the proximal end of a colonoscope into the cecal lumen relieves the pressure by removing gas through the suction channel in the colonoscope.
Colonoscopies are typically transient procedures. Colonoscopes are complex and expensive devices, and they are not placed in a patient's colon for any length of time beyond that required for visual observation, tissue biopsy or decompression. As a result, patients suffering from Ogilvie's syndrome often require a series of decompressing colonoscopies due to recurring accumulation of gas in the lumen of the colon. Martin, et al., The American Surgeon, 54: 519-521 (1988). These result in additional expense and risk to the patient.
A colonoscope provides visual information for only a small region of the colon at any given time. However, a single colonoscopy is often not sufficient to identify the source of colorectal bleeding which is typically sporadic and in many cases would be best located by observing the entire colon over a period of time.
There is therefore a need in the art for simple devices and methods for prolonged access to a patient's colon. Such devices and methods are provided by the present invention.